Ink reservoir doctor blade

ABSTRACT

The invention relates to a color chamber doctor blade  1 , which has following characteristic features: 
         two doctor blade knives  2  that can be set up in a roof-like fashion against a roller  6      from which two doctor blade knives  2  can be fixed on the doctor blade chamber body  5  by means of a clamping plate  3      whereby the clamping plate  3  is in active connection with long-stretch fasteners  4  in the axial direction (z) of the roller  6,      which are arranged essentially parallel to the clamping plate  3      and from which the force required for fixing at least one doctor blade knife  2  is applied.        

     Inventive is that the resultant of the force exercised by the fasteners  4  points to the doctor blade chamber body  5.

The invention relates to a color chamber doctor blade according to thepreamble of the claim 1.

Color chamber doctor blades have been known for a long time. The colorchamber doctor blades are subject to continuous wear and therefore mustbe replaced regularly. As a rule, to fix them, the doctor blade knivesare pressed against the doctor blade chamber body with the help of aclamping plate. For that purpose, in the past, the clamping plates werefixed with screws on the doctor blade chamber body, as shown in DE 42 41792 A1. The clamping plate, in its turn, presses the doctor blade knifeagainst the doctor blade chamber body and thus fixes it. However,because of the length of the doctor blade in the radial direction of theroller, which is impinged with color from the doctor blade chamber, alarge number of screws must be changed when changing the doctor blades.Since all kinds of set-up times lead to machine still stand and, as aresult, are expensive, various suggestions for devices have been made inthe literature that permit faster exchange of the doctor blade knives.Thus, in DE 43 20 833 C1S use of rapid-action locking devices issuggested. In recent times, one finds that the aforementioned types offixing the clamping plates of the doctor blade knives on the doctorblade chamber body are being replaced, such that

-   -   the clamping plate is in active connection with long-stretch        fasteners in the axial direction (z) of the roller,    -   which are mounted essentially parallel to the clamping plate    -   and by which the force necessary for fixing at least one of the        doctor blade knives is exercised,        as maintained in the preamble of the claim 1.

Clamping plates are flexible sheet metal plates that are held by meansof screws or similar means of fastening on the doctor blade chamberbody, however, they are not permanently fixed. Clamping is done on theside of the screws facing the roller, whereby the long-stretch fastenersin the axial direction (z) of the roller exert force on the clampingplate, which points away from the doctor blade chamber body. Theclamping plate is, however, fixed on the doctor blade chamber body bythe screws, so that the clamping plate buckles and exerts force on thedoctor blade knife, on the side of the screws facing the roller, whichis mounted on the doctor blade chamber body and thus fixes the doctorblade knife on the doctor blade chamber body. If the force exerted bythe long-stretch fasteners is inhibited, force is also neither exertedon the doctor blade knife and, if applicable, on the clamping plate.

In general, the long-stretch fasteners in the axial direction (z) of theroller are rods, with a partially round cross section, which aresupported rotatably in the doctor blade chamber body. Such rods are thenprovided with a recess or a projection, which leads to it that, onrotation of the rod, a force is exerted, whose resultant points awayfrom the doctor blade chamber. However, it is also possible to place aninflatable hose or an another body at that point, which can increase itsvolume, and in that way, exert a force on the clamping plate, whoseresultant points away from the doctor blade chamber body.

Finally it should be emphasized again that the major advantage of thistype of fastening is that, compared to the fixing of the doctor bladeknife by loosening screws, significantly lesser number of objects offastening—such as the rod for instance—need to be handled, so that itleads to significant saving of time in the changeover of the knives.

However, the described fastening systems also have their disadvantages.

As it is apparent from the above explanation and the followingdescription of the situation, a large number of screws or similarfasteners must be pushed at least through the clamping plate for theabovementioned prefixing of the clamping plates. Therefore, thedescribed doctor blade chambers have a number of holes and juts (screws)in the area of the clamping plates. Naturally, due to the unavoidablemass of the residues of the color exiting from the color deck, colordeposits precipitate precisely on the holes and the juts (screws), whichmake it difficult to cleanse the machine and, to some extent, also tochange the knives.

Consequently, the task of the present invention is to devise a doctorblade chamber, which can function with a lesser number of holes and juts(screws) in the area of the clamping plates.

This task is solved, in that

-   -   the resultant force exercised by the fasteners points to the        doctor blade chamber body.

This measure makes the supporting function for holding the screws asimplemented in the current status of the technology superfluous. Theresult is that the holes in the clamping plate and the juts (screws)protruding from the clamping plate are no longer necessary. Further,there are less impurities in the area of the clamping plate. In additionto that, one can dispense with the use of the spring steel sheet used inthe fabrication of the clamping plates, since the pressing forcenecessary for fixing the doctor blade knife and its restoring force donot result from the buckling of the sheet metal plate, but ensuedirectly from the fasteners.

Further advantages and embodiments of the invention follow from thedescription of the concrete situation and the claims.

The individual figures show:

FIG. 1. A section of a doctor blade chamber in operation according tothe current status of the technology

FIG. 2. A section of a doctor blade chamber taken out from the rolleraccording to current status of technology

FIG. 3. Top view of a clamping plate according to the current status ofthe technology

FIG. 4. A section of a doctor blade chamber in operation according tothe invention

FIG. 5. A section of a doctor blade chamber taken out from the rolleraccording to the invention

FIG. 6 An enlarged view of a cross section of the rod 4

FIG. 1 shows a color chamber doctor blade 1 according to the currentstatus of the technology. As is known, in case of the color chamberdoctor blades 1, the color chamber 8 is limited by the roller 6 to becolored of the doctor blade chamber body 5, whereby 5 can obviously alsoconsist of several parts, and the doctor blade knives 2. As adequatelydetailed in the introductory description, the two doctor blade knives 2of the color chamber doctor blades 1 are each fixed by means of aclamping plate 3, which presses the 3 respective doctor blade knivesagainst the doctor blade chamber body 5. The force required for this isthe restoring force of the clamping plate, which arises, because theclamping plate is buckled between the long-stretch fastening element 4,which is represented in this case by the rod, and the head of the screw7 and the doctor blade chamber body 5.

As already mentioned, the resultant force, which the rod 4 exerts on theclamping plate, points away from the doctor blade chamber. This forcearises because the rod 4 is provided with a recess 16 that is at thesame level with the surface of the doctor blade chamber body 5 duringthe loading of the clamping plate 3 as shown in FIG. 2. Thus therotation of the rod 4 brings the circular part of the peripheral area ofthe mainly cylindrically shaped rod 4 in contact with the clamping plate3, the contacted part of the clamping plate is pressed outside and thepreviously described restoring force of the plate 3 fixes the doctorblade knife.

FIG. 3 shows a clamping plate, which is suitable for use in the doctorblade chamber shown in FIGS. 1 and 2.

The round holes 10 and the slots 11 form the openings 9. Thereby, thediameter of the holes 10, together with the necessary play, is matchedwith the head of the screw 7, while the width of the slot 11 is matchedto the diameter of the neck of the screws. If the clamping plate is tobe removed from its operating position, the clamping plate is at firstloosened by turning the rod 4 in such a fashion that the recess comes incontact with the plate 3. Since no force or lateral buckling action onthe clamping plate 4 ensues from the rod 4 now, it is held only looselyby the screws 7. As a result, the plate is brought from its operatingposition, in which the necks of the screws grip through the grooves 11,into the removal position, thus enabling the heads of the screws 7 toslide out through the holes 10 of the clamping plate 3 for the removal.

FIGS. 4 and 5 show a chamber doctor blade according to the invention, inwhich the clamping plates 3 are provided with a top piece 13, whichincludes a joining element 14. The joining element is matched accordingto the recess 15 of the rod 4. The form of the recess 15 is shown onceagain in FIG. 6. While mounting the clamping plate 3 and the top piece13, the joining element slides along the surface 18 of the rod 4. Onstriking the joining element on the recess 15 of the rod 4, the rod 4can be turned into the clamping position. After loading the knife, theknife is clamped by rotating the rod 4. When rotating the rod 4 into theclosing direction, represented by the arrow 20, first the joiningelement slides along the even surface 18 of the recess 15, to besubsequently carried along by the shoulder 17 of the recess. The unitconsisting of the top piece 13 and the clamping plate 3 is thus broughtinto the position suitable for fixing the doctor blade knife 2.

FIG. 6 shows the top view of the clamping plate 3 which is used in thechamber doctor blades according to the invention shown in FIGS. 4 and 5.List of Reference Symbols 1 Color chamber doctor blade 2 Doctor bladeknife 3 Clamping plate 4 Fastening element 5 Color chamber body 6 Roller7 Screw 8 Color chamber 9 Opening 10 Hole 11 Slot 12 13 Top piece 14Joining element 15 Recess 16 Recess 17 Shoulder 18 Area 19 Arrow

1. Color chamber doctor blade (1) with two doctor blade knives (2) thatcan be set up in roof-like fashion against a roller (6) from which boththe doctor blade knives (2) can be fixed on the doctor blade chamberbody (5) by a clamping plate (3) and the clamping plate (3) is in activeconnection with the long fasteners (4) stretching in the axial direction(z) of the roller (6), which are arranged essentially parallel to theclamping plate (3) and from which the force required for fixing at leastone doctor blade knife (2) is applied characterized in that theresultant of the forces applied by the fasteners (4) points to thedoctor blade chamber body (5).
 2. Color chamber doctor blade (1)according to claim 1, characterized in that the clamping plate (3) isequipped with at least one specially shaped top piece (13), which formsan active connection with the long-stretch fasteners (4) in the axialdirection (z) of the roller (6).
 3. Color chamber doctor blade (1)according to claim 1, characterized in that the fasteners (4) are builtwith at least one inflatable hose, the variation in the volume of whichprovides the force required for fixing the two doctor blade knives (2).4. Color chamber doctor blade (1) according to claim 1, characterized inthat the fasteners (4) are built with at least one rod (4), through themovement of which relative to the color chamber doctor blade (1), theforce required for fixing at least one doctor blade knife (2) can beprovided.
 5. Color chamber doctor blade (1) according to claim 4,characterized in that the relative movement of the rod (4) consists of arotation around its principal axis of inertia.
 6. Color chamber doctorblade (1) according to claim 5, characterized in that the rod (4) has anessentially round cross sectional area, which has a recess (15) suitablefor clamping the clamping plate (3) or its top piece (13).
 7. Colorchamber doctor blade (1) according to claim 6, characterized in that therod (4) is fixed rotatably in the doctor blade chamber body (5). 8.Color chamber doctor blade (1) according to claim 7, characterized inthat the top piece (13) has a joining element (14), which can beinserted into the recess (15) of the cross sectional area of the rod(4).
 9. Color chamber doctor blade (1) according to claim 8,characterized in that the length of the top piece (13), the position ofthe joining element (14) on the top piece (13) and the positions of therod (4) and the recess (15) are adjusted with each other in such a waythat the joining element (14) of the clamping plate (3) located outsidethe doctor blade chamber (8) can be inserted in a form-fitting mannerinto the recess (15) at the beginning of the process of fixing of thedoctor blade knife and that the rotation of the rod (4) required forfixing the doctor blade knife (2) conveys the joining element (14) andthe clamping plate (3) into the position (a) suitable for fixing. 10.Process for the fixing of a doctor blade knife (2) of a color chamberdoctor blade (1) according to claim 1.